(1) Field of the Invention
The present invention generally relates to enhancements in devices for filtering and separating liquids. More particularly, the present invention relates to fuel filters for removing foreign particles and separating water from fuel of a fuel supply system associated with an internal combustion engine. Accordingly, the general objects of the present invention are to provide novel and improved methods and apparatus of such character.
(2) Description of the Related Art
Diesel fuel supplies frequently contain significant quantities of abrasive particles and/or water which present the potential for permanent damage to the components of the fuel injection pump and the fuel delivery system of the engine. Consequently, an effective fuel filter assembly is a practical necessity and is conventionally incorporated into the fuel supply system of a diesel engine. A multitude of conventional fuel filter assemblies employ a disposable filter cartridge which is replaced at pre-established intervals of filter usage. Such filter cartridges typically perform the dual function of removing particulate material from the diesel fuel and separating water from the fuel.
The fuel filter assemblies to which the present invention relates include a replaceable filter cartridge and a header with a base which accepts the disposable filter cartridge. The filter cartridge has a housing which defines an axial opening at one end thereof to provide fuel communication between the fuel delivery system and a filter element disposed within the cartridge housing. A sealing grommet is disposed at the axial opening to provide a fluid-tight seal. The fuel filter cartridges may house a single stage filter or a dual stage filter and may assume a wide variety of shapes and configurations.
Conventional headers used with such fuel filter assemblies include a fuel entry port which is in fluid communication with a central axial fuel conduit for transporting fuel to be filtered into the filter cartridge. Additionally, a fuel exit port of the header is fluidly connected to a coaxial fuel conduit disposed about the central fuel conduit and cooperating therewith to define a fuel exit passage therebetween. Thus, fuel to be filtered conventionally enters the filter cartridge via the central fuel conduit, is filtered therein and then exits the filter cartridge via the exit fuel passage which surrounds the central fuel conduit.
In such conventional fuel filter assemblies, a manual primer mechanism is often provided to facilitate engine starting after a spent fuel cartridge has been replaced with a fresh one. In particular, this fuel primer mechanism is disposed in the fuel flow path between the fuel entry port and the central fuel conduit such that actuation of the manual primer pump draws fuel from the connected fuel supply and forces it into the filter cartridge. While such designs can effectively prime the filter cartridge, they suffer from the deficiency that the fuel passing through the primer mechanism has not yet been filtered by the filter cartridge. Thus, the contaminated fuel passing therethrough can deposit particulate matter on the manual primer mechanism or other pump devices. These particles accumulate over time and interfere with proper performance of the primer mechanism. Naturally, this problem becomes more acute as the field life of the fuel filter assembly increases. Failure of the fuel filter assembly may be the result of this situation. This deficiency is particularly acute in fuel filter assemblies used on heavy construction equipment, such as bulldozers and cranes, due to the severe environmental conditions in which such equipment normally operates. However, the deficiency may be of concern in virtually every application.
It has been discovered that the above-described deficiency could be alleviated by reconfiguring the fuel filter assembly so that the manual primer pump is located downstream of the filter cartridge. Since, with such an arrangement, the fuel passing through the primer mechanism has already passed through the filter cartridge, very few, if any, contaminants have an opportunity to accumulate in the primer mechanism. The above-described deficiencies of conventional fuel filter assemblies can, thus, conceivably be overcome by replacing all such filter assemblies with newly redesigned devices. Such a solution is, however, highly impractical unless it could be accomplished in an efficient and cost effective manner. Moreover, the reversal of the flow path within the filter cartridge is far from straightforward because of the significant constraints of optimum space utilization in the context of providing sufficient effective filter media area.
Accordingly, there is a need in the art for improved fuel filter assemblies and methods therefor in which fuel entering the fuel filter assembly is filtered substantially immediately upon entry into the fuel filter assembly. There is a further need in the art for inexpensive fuel filter assemblies and methods therefor to retrofit conventional fuel supply systems with improved fuel filter assemblies.